This application is related to DE 198 35 373.1 filed Aug. 5, 1998 the complete disclosure of which is hereby incorporated by reference.
The invention concerns a method for labeling the outer surface of a wind shield body of a microphone made from foamed material and an associated microphone wind shield. The term xe2x80x9clabelingxe2x80x9d refers not only to letter sequences but also to graphical representations and combinations of both.
Wind related noises can disturb microphones used for reporting or other sound recordings, in particular outside of buildings. Microphones are therefore conventionally provided with a wind shield made in general from a foamed material body, comprising a bore for sliding onto the microphone. The wind shield has been used, for some time, as an information or advertisement carrier in particular for TV reports or interviews. TV companies therefore usually have their logo or name applied to the wind shield so that it is clearly visible in TV broadcasts.
Letter sequences are usually applied to a wind shield body milled from a foamed material block by spraying paint using the screen printing method. It has turned out, however, that highly accurate, fine structures cannot be produced by this method. Moreover, the sprayed paint becomes brittle with time and crumbles away thus rendering the letter sequence unsightly so that the wind shield can no longer be used.
It is the underlying purpose of the invention to introduce a method for applying a letter sequence onto the outer surface of a wind shield of a microphone made from foamed material which permits application of the letter sequence in a long-lasting and highly accurate fashion, and also to provide a corresponding microphone wind shield.
This object is achieved in accordance with the inventive method by sequentially carrying out the following steps:
producing at least one letter sequence element on a carrier;
positioning the carrier on the outer surface of the wind shield by interposing an adhesive which can be activated by heat;
application of thermal energy using radiation to activate the adhesive; and
removing the carrier after the adhesive has cooled and solidified, wherein the letter sequence element remains on the outer surface of the wind shield body.
The invention is based on the idea of not forming the letter sequence during application onto the wind shield body, as in conventional screen printing, but to initially prefabricate the letter sequence on a carrier as a separate structural member. The carrier may be, in particular, a flexible carrier foil or another flat, flexible carrier. If the letter sequence consists of several individual elements, e.g. letters, which have to be accurately positioned with respect to one another, this can be taken into consideration during production of the letter sequence on the carrier to ensure an accurate relative position of the individual letter sequence elements.
The letter sequence element(s) is/are disposed on the carrier such that the surface which is to be connected to the wind shield body is exposed. A heat-activating adhesive is disposed onto this surface, e.g. by spraying. The carrier is then positioned on the outer surface of the wind shield body in such a fashion that the heat-activating adhesive of the letter sequence elements seats on the wind shield body.
Thermal energy is subsequently applied, without contact, for activating the adhesive i.e. using radiation. Towards this end, ordinary heat radiation can be used. However, the thermal energy is preferably applied using laser beams, wherein the laser beams can be guided with high accuracy over the adhesive surface to be heated.
Activation of the adhesive firmly bonds the letter sequence elements to the wind shield body. The letter sequence elements are fixed on the carrier with an adhesive strength which is less than the adhesive strength holding the letter sequence elements on the wind shield body via the heat-activating adhesive. When the carrier is removed after cooling and solidification of the adhesive, the letter sequence elements are detached from the carrier and remain on the outer surface of the wind shield body to thereby form the letter sequence.
Application of thermal energy, in particular using laser beams, generates an activation temperature for the adhesive which should be considerably less than the melting temperature of the foamed material of the wind shield body. The adhesive is preferably heated to between approximately 90xc2x0 and approximately 100xc2x0, thereby reliably preventing damage to the wind shield body.
In a preferred embodiment of the invention, the letter sequence elements are generated and transferred using the so-called flock transfer method. Therein, a melting adhesive is disposed on a fully flocked, flexible flat carrier in correspondence with the configuration of the letter sequence element(s). The melting adhesive glues the flock fibers to form a continuous letter sequence element in correspondence with the configuration in which it is disposed. The adhesive thus produces, on the one hand, a continuous letter sequence element on the completely flocked carrier and on the other hand, can fix the letter sequence element to the wind shield body when subsequently reactivated by the laser beams.
If the letter sequence element comprises only one color, a carrier can be used whose complete surface is flocked in a desired color. Alternatively, the completely flocked carrier can be painted with at least one color before application of the adhesive using, in particular, a screen printing spray. When the pre-fabricated letter sequence consisting of one or more letter sequence elements formed and fixed on the carrier is to be transferred to the wind shield body, the carrier is first positioned and fixed to the outer surface of the wind shield, preferably by means of needles or a heat-resistant adhesive tape. Other removable mounting means are also feasible which can withstand the thermal energy applied by the laser beams.
With respect to the microphone wind shield, the above-mentioned object is achieved in that the letter sequence is glued onto the outer surface of the wind shield body, consisting of foamed material, in the form of a pre-fabricated structural component. Further features of the microphone wind shield can be extracted from the above description of the method.